1. Field of the Invention
The following invention relates to keyboards, and more particularly to a keyboard formed in two or more mutually pivotable segments which may be adjusted and locked into a number of different ergonomic positions.
2. Description of the Prior Art
Known keyboards of the type used at a computer terminal, for example, generally include a unitary board onto which alphanumeric keys are attached. It is a disadvantage of such known keyboards that the wrists and/or arms and shoulders of an operator must be contorted into a configuration which is stressful to the user after prolonged use of the keyboard. This problem is brought about by the fact that the hands of the user must be turned outwardly by pivoting of the wrists relative to the forearms, resulting in ulnar deviation. Discomfort to the user caused by pronation of the wrists is also a problem with these known keyboards. Pronated posture can also transmit stresses into the neck and shoulders of the user.
It is desirable to reduce pronation and ulnar deviation of the wrists in computer keyboards. To that end, U.S. Pat. Nos. 5,424,728 and 5,543,790 describe adjustable keyboards with at least two segments which are movable relative to one another via a hinge or joint. By moving the segments, the orientation of the user's wrists and hands can be adjusted to allow for reduction of ulnar deviation and pronation of the wrists. The hinge or joint in those patents is disclosed as preferably being a ball and socket-type joint.
U.S. Pat. Nos. Des. 362,434 and 5,454,652, assigned to Lexmark and U.S. Pat. No. 5,527,116, assigned to Maxi Switch, each show adjustable keyboards including a mechanism for locking the keyboard segments in place. However, in each of the keyboards described in those patents, the locking mechanism includes a large number of parts. As a result, those keyboards can be difficult to manufacture and assemble and therefore can be expensive, and those keyboards can be difficult for the user to adjust and lock.